#5 Automatic palette reductions when exporting palette images

[Anonymous]

If user chooses to export palette image type, pngcrush
should automatically truncate unused colours in the
palette, and reduces bit depth where appropriate,
without using -plte_len switch.

[Glenn Randers-Pehrson]

I wrote the PNG palette-reduction for ImageMagick. It was a huge undertaking that I don't want to duplicate in pngcrush. I recommend doing a first pass with ImageMagick, then using pngcrush on the result.